In an intake system for a multi-cylinder internal combustion engine, an intake device (intake manifold) including an intake chamber connected to an air inlet and a plurality of branch passages that branch off from the intake chamber in correspondence to the intake ports of the respective cylinders is used. In such an intake device, it is often the case that the branch passages are arranged in line with each other in a manner similar to the arrangement of the cylinders, and are connected with the intake chamber in a row. However, in such an intake device, a branch passage disposed at an end portion in the direction of the arrangement and a branch passage disposed at a central portion have different positional relationships with the other branch passages, and this may cause a difference between the amounts of air taken in the cylinders, which in turn may result in a difference in the air-fuel ratio. To address this problem, in some intake devices, the branch passages are connected at positions rotationally symmetric about a predetermined center line of the intake chamber such that the relative positions of the branch passages are the same (symmetric) (e.g., Patent Documents 1-3).